(1) Field of the Invention
The present invention relates to electro-active sensors, and more particularly, to a electro-active sensor, method for constructing the same; apparatus, and circuitry that are used to detect electro-active species in solution.
(2) Description of Related Art
Electro-active sensors have long been known in the prior art. The sensors have been used in a myriad of applications, two examples of which include detecting low-levels of electrochemically active species found in drinking water used on the International Space Station (ISS) Alpha and detecting metabolic products produced by biofilms to better understand their life-cycle activities. In pursuing these goals, a number of electrochemical cells and sensors have been developed. They include Ion Selective Electrodes (ISE's), Galvanic cells, conductivity sensors, redox cells, and pH sensors.
Redox and conductivity sensors are used to characterize ionic species in solution and are based on a traditional three-element electrochemical cell. Commercially available three-element electrochemical cells typically consist of individual pencil like metal electrodes that are placed in solution and used to detect ionic species in the solution by measuring an electrochemical cell current as voltage is scanned.
While functional, electrochemical sensors currently available suffer from several drawbacks. Traditional sensors are fabricated at an end of a pencil-like cylindrical tube. Such sensors cannot be configured easily in a multi-sensor array, nor can they be readily miniaturized.
Additionally, because of their configuration, conventional sensors generally have short useful lives, with a long life typically being one month in natural waters and up to six months in drinking waters. When used in bioreactors, the sensors typically have life expectancies of a few days. Because of their short useful lives, traditional sensors are impractical for measuring water quality in applications where testing must take place for many months or years, such as on the ISS, and during a long trip to Mars. Thus, long-life sensors that remain useful for three to five years are needed.
Therefore, it can be appreciated that there exists a need for an electrochemical cell that is planar, that is easy to clean, that lends itself to long-life usage, and that may be miniaturized. In this regard, the present invention substantially fulfills these needs.